As is widely recognized by the medical community, heart disease is the number one contributor to premature death in this country, and coronary stenosis, i.e., the progressive narrowing of the coronary artery caused by a build-up of plaque on the inner arterial wall, is by far the most pervasive form of this disorder. As the coronary artery becomes progressively narrower, the blood supply to the heart muscle is consequently reduced, and thus greatly increases the risk of thrombosis and myocardial infarction in the individual afflicted with such condition.
In this country alone, coronary stenosis kills approximately half (1/2) a million people every year. Unfortunately, due to the fact that sudden death is one of the most common manifestations of coronary stenosis, a substantial number of those killed by coronary stenosis die before any kind of emergency medical treatment can be administered. In fact, this aspect of heart disease is so prevalent that in the United States alone, the cost of coronary care--the medical treatment of heart problems--substantially exceeds one hundred billion dollars ($100,000,000,000.00) annually.
While numerous attempts have been made to develop methods for detecting the presence of arteriosclerosis before it advances to a critical stage, to date, none have proven successful. In this regard, such methods have suffered from the drawback of not providing reliable results that can be readily interpreted. For example, U.S. Pat. No. 4,905,706, issued to Duff et al, discloses a method and apparatus for the detection of heart disease based upon an analysis of the characteristic sounds of the heart. Such technique is based upon the analysis of a few milliseconds of a phonocardiogram (PCG) occurring between certain identified heart sounds. Specifically, such sounds analyzed involved those which occur after diastolic blood flow begins, and are initiated by the third heart sound S3, and terminating by the fourth heart sound S4, this interval lasting approximately one hundred and thirty-three milliseconds thereafter. Because such interval is so brief and so difficult to detect, the results produced by the techniques disclosed in U.S. Pat. No. 4,905,706 are generally unreliable. Indeed, in order to insure any degree of accuracy, an electrocardiogram (ECG) must necessarily be utilized in performing the procedures disclosed in U.S. Pat. No. 4,905,706, which as a consequence substantially increases the costs of performing such procedures.
Moreover, while other devices and techniques are available for use in monitoring various cardiac parameters, such techniques, which include ultrasonic and electrocardiographic, require complex, expensive equipment. As such, such screening procedures cannot feasibly be conducted on a large scale for the general population.
It would therefore be desirable and advantageous to devise a simple, safe, and non-invasive method and apparatus for identifying coronary stenosis. Ideally, such device would be usable by technicians and other non-medical personnel in screening large groups of people, without the need for special medical facilities and the like. There is further need in the art for such a method and apparatus for the early detection of coronary stenosis that utilizes conventional diagnostic equipment and can be utilized at substantially reduced cost relative to conventional techniques in use for monitoring various cardiac parameters. There is still further a need for methods and apparatus for the early detection of coronary stenosis that is capable of producing continuously reliable results, irrespective of the patient population with which the same are utilized.